We are pursuing an in-depth investigation into the structure and function of the membrane receptor for IgE. For these studies, intact cells from a rat basophilic leukemia, as well as normal rat mast cells, are being used. In addition, receptor-bearing membrane vesicles and solubilized receptors are being studied. The aim is to understand the structure of the receptor and its integration in the plasma membrane. Results of such studies, as well as direct functional studies, are aimed at understanding the early stimulation of cells by antigen-induced, antibody-mediated reactions.